1. Field of the Invention
The present invention relates to an electronic apparatus having a fuel cell which generates current through chemical reaction. More particularly, the present invention relates to an electronic apparatus capable of sufficiently supplying air to a fuel cell without a separate air pump or fan.
2. Description of the Related Art
Recently, a portable fuel cell has been developed as a compact portable electric power. This portable fuel cell is superior to a portable electrical power supply which drives a generator and generates electricity via engines. That is, compared with the portable electrical power supply, such a portable fuel cell generates electricity equal to hundreds of watts, exhausts less air pollutants and causes less noises.
In general, the portable fuel cell has a fuel cell body in which phosphoric acid fuel cells are stacked. Also, an air supply fan or a metal hydride tank is housed in a casing. Here the air supply fan supplies air to a fuel cell body and the metal hydride tank supplies hydrogen as a fuel gas. During operation, the portable fuel cell generates electricity using air transported by the air supply fan and hydrogen supplied from a hydrogen supply source.
Conventionally, the portable fuel cell is designed to be operable with the construction which is as simple as possible. Here, the portable fuel cell cools a fuel cell body with air transported from the air supply fan to the fuel cell body. Also, high-temperature air exhausted from the fuel cell body is used to raise temperature of the metal hydride tank.
To release unreacted fuel cell gas out of the fuel cell body, the portable fuel cell is typically equipped with a catalystic combustor for processing unreacted hydrogen. The catalystic combustor includes a catalyst layer having for example a platinum catalyst, where catalystic combustion is performed using a mixture of the unreacted hydrogen and air.
The fuel cell generates current smoothly when sufficiently supplied with air including oxygen. But this natural convection method disadvantageously fails to ensure sufficient air supply to the fuel cell. To overcome this drawback, air is forcibly supplied to between the stacked cells using a separate fan.
The conventional fuel cell will be explained in greater detail hereunder with reference to FIG. 1.
FIG. 1 is a perspective view illustrating the conventional fuel. For explanatory purpose, in FIG. 1, a narrow A indicates a forward direction, and a direction perpendicular to the arrow A is referred to as a horizontal direction.
As shown in FIG. 1, the conventional fuel cell includes a phosphoric acid fuel cell body 2, a metal hydride tank 6, an air supply fan 8, a catalystic combustor 10, a DC-DC converter and a controller. The phosphoric acid fuel cell body 2 is housed in a casing 1 and supplied with hydrogen and air to generate electricity. The metal hydride tank 6 supplies hydrogen stored to the fuel cell body 2. The air supply fan supplies air to the fuel cell body 2. Also, the catalystic combustor 10 processes unreacted hydrogen discharged from the fuel cell body 2. The DC-DC converter controls voltage of power supplied to the outside at a uniform level. A controller (not shown) controls operation of each unit.
To form a fuel stack 3, a predetermined number (e.g., 30 plates) of rectangle-shaped phosphoric acid power-generating cells are stacked horizontally via a bipolar plate. Here, the plates of the stack are fastened at both ends individually. In the fuel cell body 2, hydrogen gas supplied to a distribution manifold 4 travels downward inside the fuel stack 3 and then into the power-generating cells. In turn, unreacted hydrogen travels back to a recovery manifold 5. Meanwhile, air supplied onto the fuel stack 3 travels downward inside the fuel stack 3 and into the power-generating cells. At the same time, the fuel cell body 2 is air-cooled and high-temperature air is released to a rear side of the fuel cell stack 3.
The casing 1 has partitions 31, 32 and 33 formed on rear, upper and front sides of the fuel cell 2. The casing 1 is divided into front and rear sides by the partition 31, and a rear space 34 is formed behind the partition 31. Also, a front space of the partition 31 is divided into upper and lower sides by the partition 32. An upper space 35 is formed in an upper part of the partition 32. Furthermore, a lower space of the partition 32 is divided into front and rear sides by the partition 33 and a front space 36 is formed in front of the partition 33. In addition, the partitions 31 and 33 each have an opening for circulating air disposed corresponding to the fuel stack 3.
The metal hydride tank 6 is connected to a plurality of metal hydride tank elements 6a filled with metal hydride. The metal hydride tank 6 is mountable in the rear space 34. Also, the metal hydride tank 6 and the distribution manifold 4 are connected to a hydrogen introduction pipe (not illustrated) and hydrogen is supplied to the distribution manifold 4.
The air supply fan 8 has an intake hole 8a formed in a central part thereof and a ventilator 8b formed in a lower part thereof. The air supply fan 8 is disposed in an upper part of the front space 36 in the upper space 35. A catalystic combustor 10 includes a rectangular parallelepiped external plate 11, a bar-shaped hydrogen supply nozzle, and a catalyst layer 13. The external plate 11 has upper and lower sides wide opened. The hydrogen supply nozzle 12 is inserted into an upper space of the external plate 11. The catalyst layer 13 is filled in a lower space inside the external plate 11. The catalystic combustor 10 is fixed in a front portion of the front space 36, in particular to a support plate 37 installed under the partition 32 inside the front space 36.
Furthermore, the support plate 37 has openings 37a and 37b formed therein so that air from above is distributed to middle and external sides of the catalystic combustor 10 at an adequate ratio and travels downward. Also, the hydrogen introduction pipe is provided between the recovery manifold 5 and the hydrogen supply nozzle 12 to induce unreacted hydrogen. The catalyst layer 13 has a platinum catalyst formed on a honeycomb which causes catalytic combustion to a mixture of the unreacted hydrogen and air passing therethrough.
In this catalystic combustor 10, the unreacted hydrogen from the recovery manifold 5 is subject to catalystic combustion using air received from thereabove. Then, high temperature combustion gas is released from an underside of the catalystic combustor 10. The DC-DC converter and controller are superimposed one upon another in the upper space 35. In addition, air intake holes 41 are formed according to locations of the DC-DC converter and controller. A driving heater (not illustrated) is provided to heat air transported to the fuel cell body through the air intake holes 41.
This conventional fuel cell is necessarily equipped with the air supply fan 8 for supplying air to the fuel stack 3 and the driving heater for heating the air supplied. This complicates internal construction of the fuel cell and subsequently a manufacturing process thereof, thereby increasing manufacturing costs and hampering miniaturization thereof.
Moreover, the air supply fan 8 and the driving heater run with a lot of noise, rendering their use inconvenient. Further, disadvantageously, additional power is required to operate the air supply fan 8 and the driving heater. Especially, the fuel cell, when employed in a note book computer requires a cooling fan for cooling and the air supply fan 8 independently, thereby disadvantageously aggravating noises.
Also, to generate current, the fuel cell performs chemical reaction most actively when air supplied has a temperature of 60° C. to 70° C. Thus in a case where low-temperature air is supplied to the fuel cell due to low ambient temperature, the fuel cell experiences considerable decline in its capability.